From bottom to top, they are faithful reproductions of:
• AR-15 prototype w/ 25 round magazine. Note the trigger charging handle. Only a handful produced.
• Colt 601 (early), very few produced.
• Colt 601 (late), the Project AGILE and early SF rifle in Vietnam. 8,500 produced in September of 1963.
• Colt 602, the early adoption USAF rifle, also used by US special operations units early in the war. 19,000 produced in April 1963.
• Colt 603/XM16E1 or M16A1, original US Army contract rifles, produced for the “one-time buy” in November of 1963, and subsequently produced throughout the 1960s and 1970s. Early examples of this model and all previous rifles did not have chrome-lined chambers or bores, which caused serious problems in Vietnam if the barrels were not kept clean and free of moisture – this rifle features the later full-fence lower, and thus may or may not have a chrome-lined barrel.
Colt 604, US Air Force contract rifle, produced alongside the Army’s XM16E1 as part of the November 1963 order.
• Colt 605, original attempt at an M16 carbine. This rifle, unlike later visually similar “dissipator” carbines tapped gas from the visible gas block. Due to the bullet’s prompt exit from the barrel after passing the gas block, the rifles were undergassed and unreliable.
• Colt 606, the original heavy-barreled squad support variant of the M16. This was the first version of the M16 to feature a heavier barrel, though its profile is heavy under the handguards, unlike the later M16A2 (Colt 705).
• Colt 607, the first AR-15 model to feature a collapsing buttstock. Very few of these were ever made. The line of development of carbine AR-15s begun with this rifle would eventually lead directly to today’s M4 Carbine.
• Colt 608, the “Aircrew Survival Carbine”, designed to be stowed in an aircraft and used if the aircraft were downed. Like the 607, very few were ever made.
• Colt 609, the famous XM177E1, along with the Colt 610/XM177 US Air Force “slick side carbine”, it was the first successful AR-15 carbine, and was used extensively by US special operations units in Vietnam. It was fitted with a moderator to reduce the noise and blast from the short 10″ barrel.
• Colt 629/XM177E2, this rifle improved upon the XM177/E1 by utilizing the full fence lower of the A1 M16, as well as lengthening the barrel to 11.5″ to improve velocity. It used an improved moderator design that, along with the longer barrel, helped further reduce the noise and blast of firing.